In recent years, still larger capacities of storage systems managed by, for example, a server are pushed forward. To build a large-capacity storage system, a drive array apparatus capable of realizing high reliability and high performance is indispensable. The drive array apparatus is also called a RAID (Redundant Array of Independent Disks) apparatus or a disk array apparatus. The drive array apparatus may be denoted as the RAID apparatus below.
Normally, a RAID apparatus includes a plurality of hard disk drives (HDDs). In recent years, a hybrid configuration using a plurality of HDDs and SSDs (solid state drives) is also developed for a RAID apparatus. Incidentally, HDD and SSD may generically be denoted as the data storage drive.
When a specific storage area of a constituent HDD fails, a RAID apparatus restores data recorded in the storage area and copies all data of the HDD to a spare data storage drive (hereinafter, simply a spare drive). The RAID apparatus can be reconfigured by such rebuilding.
When a RAID apparatus is reconfigured by rebuilding as described above, an HDD in which a failure has occurred in a specific storage area is made unavailable and the HDD is replaced by another HDD. Thus, the execution time needed for rebuilding including the work time for HDD replacement increases, leading to a heavy burden of storage system operation including the cost of HDD replacement. Against such a background, improved RAID apparatuses allowing continued use of an HDD have been proposed.
A conventional improved RAID apparatus uses a management table that manages the storage area (accessed by LBA) for each head of each HDD to perform rebuilding that restores data of the storage area corresponding to a failed head. Such rebuilding allows continued use of HDDs by inhibiting HDD replacement. However, such rebuilding requires a large-capacity management table that manages all LBA corresponding to each head and a great deal of time is needed for processing to reference and update the management table. Therefore, while the continued use of HDDs is possible, the execution time needed for rebuilding may not be reducible in the end.